5-Aminobenzimidazole → HCID 178507337, compound

Participants

Reaction Steps

To a solution of 1.08 g of 5-aminobenzimidazole in 20 mL of glacial acetic acid are added 2.68 g of sodium acetate. To this solution is added dropwise 0.4 mL of bromine. The resulting brown precipitate is stirred at room temperature for 2 hours. The reaction mixture is rotary evaporated and the residue is diluted with water and ethyl acetate. The mixture is basified with 1 N sodium hydroxide and decanted. The organic layer is washed with water followed by brine. The aqueous layers are extracted with ethyl acetate; the combined organic layers are dried over magnesium sulfate, filtered and rotary evaporated. The residue is purified by flash column chromatography on silica gel, eluting with 12.5 to 16.5% methanol/methylene chloride followed by recrystallization from hexanes/ethyl acetate to provide 887 mg of 5-amino-4-bromobenzimidazole as a pale brown solid.

Provenance & Evidence